This invention relates to improved radio receiving apparatus and, more particularly, to such apparatus which includes headphones coupled by a cable to a receiving unit, wherein the cable functions to supply audio signals from the receiving unit to the headphones and also as an antenna to pick up and couple radio signals to the receiving unit.
For proper operation of radio receiving apparatus, and particularly stereophonic radio receivers, it is conventional to connect a radio antenna to the receiving apparatus, at least to the high frequency "front end" section therein. Typically, such as in the environment of a home entertainment system, a relatively large outdoor antenna is coupled by suitable leads, such as coaxial cable, twin line transmission leads, or the like, to the usual radio frequency (RF) stage of the receiving apparatus. Such large antennae are substantially immobile; and the radio receiving apparatus with which they are used are of the so-called stationary type.
Portable radio receivers likewise are provided with antennae. When such receivers are adapted to receive FM broadcast transmissions, and particularly FM stereophonic signals, the antenna that is used therewith typically may be the so-called "rod-antenna". The rod-antenna generally is constructed as a telescoping rod that is pivotally connected to the receiving apparatus and, thus, may be extended and positioned in different directions so as to optimize signal reception. However, the need to adjust the directivity of the rod-antenna in order to improve sensitivity, depending upon different positions and locations of the receiver apparatus, may be troublesome to the operator. Also, when in its extended position, the rod-antenna may interfere with other individuals, may present an obstacle to other property, and may become a relatively dangerous or hazardous instrumentality. Moreover, the rod-antenna may be easily damage or even destroyed.
In relatively compact radio receiving apparatus, the receiving unit may omit the usual loudspeakers; and audio signals may be reproduced for the user by means of headphones, such as stereo headphones. Of course, the headphones are coupled to the receiving unit by a cable such that the audio frequency signals which are produced by the receiving unit in response to incoming radio signals may be coupled to and transduced by the headphones. Typically, a jack/plug connection is provided between the headphone cable and the receiving unit. If a rod-antenna also is provided in the receiving unit, significant interference may occur between that antenna and the headphone cable.